Building LLVM with Alive instead of InstCombine.

1. Generate C++ for optimization suite

> python gen.py < suite.opt > alive.inc

2. Copy contents of alive.inc into InstructionCombining.cpp, where it says
"Insert InstCombiner::runOnInstruction here".

3. Change header of runOnInstruction to "InstCombiner::runOnInstruction".

4. Replace InstCombine.h and InstructionCombining.cpp in a fresh copy of LLVM 3.4.1
with the versions in this directory.

5. Configure and compile.
